Apparatus for scrubbing substrate

ABSTRACT

Improved method and apparatus for scrubbing a substrate are provided, the method including the step of scrubbing one face of the substrate with a cylindrical rotary brush while applying back pressure to the substrate by jetting a fluid for generating back pressure against the other face of the substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to method and apparatus for scrubbingeither face or both faces of a substrate with a cylindrical brush whilechucking only the periphery of the substrate,

2. Description of the Prior Art

Recently, semiconductor devices have been evolved from very large scaleintegration (VLSI) into ultra large scale integration (ULSI). On asurface of a semiconductor substrate, very minute circuits are denselyformed using a precision photolithographic technique. In the productionprocess, microscopic dust particles adhering on the surface of thesemiconductor substrate will result in defective semiconductor circuitsand reduce the production yield. The production cost steeply rises, asthe degree of integration of semiconductor devices increases. Therefore,an improvement in the production yield will largely contribute to thecost reduction, and the removal of dust particles is a very importantsubject.

At the production site of semiconductor devices, although the cleaningof the front face of a semiconductor substrate on which microcircuitsare formed is strictly controlled, control on the cleaning of the backface is not so strict at present. During the production processes, theback face of the semiconductor substrate is brought into contact withsuction bases of equipment and handling devices, and becomescontaminated. The contamination of the back face is found to be one ofthe causes of the contamination of the front face.

Though sufficient cleaning of the back face of the semiconductorsubstrate has recently been added to the production process, there stillexist problems as follows:

(1) Since microcircuits are densely formed on the front face of asemiconductor substrate as previously mentioned, the substrate cannot besupported at the front face thereof for the scrubbing of the back facethereof. Accordingly, the semiconductor substrate has to be supported bychucking the periphery of the substrate with a chuck jaw withoutsupporting a central portion of the front face of the substrate for thescrubbing of the back face. However, since a chuck jaw for chucking theperiphery of the substrate slightly projects outwardly of the scrub faceof the substrate, a disk brush as shown in FIG. 21 which has a smallscrubbing area and hence is of an insufficient scrubbing ability isconventionally used for the scrubbing.

(2) When the back face of the semiconductor substrate is scrubbed with ascrubbing means such as a brush with its periphery being chucked by thechuck jaw as described above, the thin semiconductor substrate is warpedby the contact pressure of the brush, so that a central portion of thesubstrate cannot be sufficiently scrubbed.

(3) Since the chuck jaw projects outwardly of the scrub surface of thesemiconductor substrate as described above, peripheral portions of thesubstrate adjacent the projections of the chuck jaw cannot besufficiently scrubbed, and some part of the scrub surface remainsunscrubbed.

Another problem associated with the production of semiconductor devicesis dust particles suspended in the air. Although a production apparatusfor semiconductor devices which is related to the present invention isused in a clean room and the amount of dust particles suspended in theair is significantly reduced, there exists a very small amount ofsuspended dust particles. After the scrubbing of the substrate, thesedust particles will adhere onto the surfaces of the substrate charged bystatic electricity, and the scrubbed surface of the substrate willbecome contaminated.

In view of the problems associated with the prior art, it is an objectof the present invention to provide method and apparatus for scrubbing asubstrate which present an enhanced scrubbing ability.

It is another object of the present invention to provide method andapparatus for scrubbing a substrate which prevent a central portion ofthe semiconductor substrate from being warped by the contact pressure ofa brush during the scrubbing operation so as to sufficiently scrub eventhe central portion.

It is still another object of the present invention to provide methodand apparatus for scrubbing a substrate which are capable of scrubbingeven peripheral portions of the substrate lying very close to theprojections of a chuck jaw for chucking the substrate.

It is a further object of the present invention to provide method andapparatus for scrubbing a substrate which prevent suspended dustparticles from adhering onto the substrate by removing electrostaticcharge after the scrubbing of the substrate.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda method for scrubbing a substrate comprising the step of scrubbing oneface of the substrate with a cylindrical rotary brush while applyingback pressure to the substrate by jetting a fluid for generating backpressure against the other face of the substrate.

With this method, while only the periphery of the substrate is chucked,even a central portion of the substrate can forcibly be scrubbed byvirtue of the back pressure applied thereto, and no portion of thesurface remains unscrubbed.

According to a second aspect of the present invention, there is provideda method for scrubbing a substrate comprising the step of scrubbing bothfaces of the substrate with cylindrical rotary brushes disposed on theboth sides of the substrate symmetrically with respect to the substrate.

With this method, the pressure applied to one face of the substrate isbalanced with the pressure applied to the other and, hence, even acentral portion which is difficult to scrub can be effectively scrubbedwithout warpage of the substrate.

Preferably, the method according to the first or second aspect of thepresent invention further comprising the step of, after scrubbing thesubstrate, drying the substrate and then removing electrostatic chargefrom the substrate with a charge removal means.

The substrate is brought into contact with a cylindrical rotary brushand a wash liquid when scrubbed, and then centrifugally dried byrotating the substrate at a high speed. At this time, the frictioncaused by the contact between the substrate and the cylindrical rotarybrush and/or wash liquid (especially where the wash liquid is highpurity water) and between the substrate and the ambient air sometimesgenerates electrostatic charge on the substrate. Such electrostaticcharge can be effectively removed by the aforementioned charge removingmeans. This prevents dust particles suspended in the air from adheringonto the substrate and enables the substrate to be kept clean after thescrubbing.

According to a third aspect of the present invention, there is providedan apparatus for scrubbing a substrate, comprising: a substrate chuckadapted to surround the substrate and having a clamp groove formedtherein for receiving a periphery of the substrate; a cylindrical rotarybrush adapted to contact a scrub face of the substrate for scrubbing thescrub face from one end to the other; a back pressure paddle for jettingfluid against an opposing face of the substrate to apply back pressureto the substrate; and a rotation mechanism for rotating one of thesubstrate chuck and the cylindrical rotary brush within a plane parallelto the substrate, wherein said substrate chuck includes chucking jawsprojecting inwardly from the clamp groove of the substrate chuck tosupport the substrate such that the entire scrub face is exposed to thecylindrical rotary brush, the jaws are not exposed to the brush, and theopposing face is exposed to the back pressure paddle.

With this apparatus, the substrate is scrubbed with only the peripherythereof being chucked while a high contact pressure is applied to acentral portion of the substrate; thus, even the central portion whichhas been unable to be sufficiently scrubbed by a conventional apparatuscan be effectively scrubbed. Since the chuck jaw for chucking theperiphery of the substrate is adapted to be positioned inward relativeto the face to be scrubbed of the substrate, the brush never contactsthe chuck jaw. Therefore, the brush can be moved extensively even beyondthe circumference of the substrate to scrub the substrate. This ensuresan improved scrubbing efficiency and minimizes an unscrubbed portionremaining in the periphery of the substrate.

According to a fourth aspect of the present invention, there is providedan apparatus for scrubbing a substrate, comprising: a substrate chuckadapted to surround the substrate and having a clamp groove formedtherein for receiving a periphery of the substrate; upper and lowercylindrical rotary brushes provided on both sides of the substrate forcontacting both faces of the substrate from one end to the other endthereof for scrubbing both faces of the substrate; and a rotationmechanism for rotating one of the substrate chuck and the upper andlower cylindrical rotary brushes within a plane parallel to thesubstrate, wherein said substrate chuck includes chucking jawsprojecting inwardly from the clamp groove of the substrate chuck, suchthat the substrate is supported therein to expose each entire substrateface to the respective upper and lower cylindrical rotary brushes andnot to expose the jaws to the brushes.

With this apparatus, in addition to the advantages of the foregoingapparatus according to the third aspect, the both faces of the substratecan be simultaneously scrubbed.

According to a fifth aspect of the present invention, there is providedan apparatus for scrubbing a substrate comprising: a substrate chuckadapted to surround the substrate and having a clamp groove formedtherein for receiving generally entire peripheral portion of thesubstrate and fluid drain through-holes provided along the clamp grooveand extending from the upper surface to the lower surface thereof; aback pressure paddle for jetting fluid for generating back pressureagainst the face opposite a face to be scrubbed of the substrate toapply back pressure to the substrate; a cylindrical rotary brush adaptedto contact the face to be scrubbed of the substrate for scrubbing thesame; and a rotation mechanism for rotating the substrate chuck or thecylindrical rotary brush within a plane parallel to the substrate.

The fluid for generating back pressure discharged from the back pressurepaddle onto the substrate is thrust away toward the circumference of thesubstrate by the centrifugal force generated by the rotation of thesubstrate chuck, and is effectively drained from the fluid drainthrough-holes provided along the clamp groove. Therefore, the uppersurface of the substrate can be kept clean.

In addition, where the water adhering on the substrate is centrifugallyremoved by rotating the substrate at a high speed after the completionof scrubbing, the water removed is effectively drained from the fluiddrain through-holes.

According to a sixth aspect of the present invention, there is providedan apparatus for scrubbing a substrate comprising: a substrate chuckadapted to surround the substrate and having a clamp groove formedtherein for receiving generally entire peripheral portion of thesubstrate and fluid drain through-holes provided along the clamp grooveand extending from the upper surface to the lower surface thereof; upperand lower cylindrical rotary brushes provided on both sides of thesubstrate and adapted to contact both faces of the substrate,respectively, for scrubbing the both surfaces of the substrate; and arotation mechanism for rotating the substrate chuck or the upper andlower cylindrical rotary brushes within a plane parallel to thesubstrate.

With this apparatus, like the fifth case, wash water will not remain onthe upper face of the substrate but is smoothly drained even in asimultaneous two-face scrubbing operation, resulting in an effectivesimultaneous two-face scrubbing operation.

Preferably, the apparatus according to any one of the third to sixthaspects of the present invention further comprises a charge removalmeans provided in a substrate scrubbing station and/or a substratetransporting path for removing electrostatic charge on the substrateafter the completion of scrubbing.

As with the scrubbing methods stated above, the electrostatic chargegenerated on the substrate during or after scrubbing is effectivelyremoved with the charge removal means. Therefore, the substrate will notattract dust particles suspended in the air and can be kept clean afterscrubbing.

For a more complete understanding of the above and other features andadvantages of the invention, reference should be made to the followingdetailed description of preferred embodiments of the invention, and tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a plan view wholly showing a scrubbing apparatus in accordancewith the present invention;

FIG. 2 is a vertical sectional view of a scrubbing station of ascrubbing apparatus in accordance with the present invention;

FIG. 3 is a vertical sectional view in an orthogonal relation to FIG. 2;

FIG. 4 is a plan view of the scrubbing station in an opened state;

FIG. 5 is a plan view of the scrubbing station in a closed state;

FIG. 6 is an enlarged sectional view for illustrating the relationbetween a substrate and a clamp groove in accordance with the presentinvention;

FIG. 7 is a sectional view of the body portion of the scrubbing station;

FIG. 8 is a partial plan view of a lock mechanism in accordance with thepresent invention;

FIG. 9 is a front view of the lock mechanism shown in FIG. 8;

FIG. 10 is a partial side elevational view illustrating the lockmechanism before operation;

FIG. 11 is a partial side elevational view illustrating the lockmechanism after operation;

FIG. 12 is a schematic sectional view illustrating the scrubbing stationbefore supplying a substrate;

FIG. 13 is a schematic sectional view illustrating the scrubbing stationsupplied with a substrate;

FIG. 14 is a schematic sectional view illustrating the scrubbing stationin scrubbing operation;

FIG. 15 is a schematic sectional view illustrating the scrubbing stationin both-face scrubbing operation;

FIG. 16 is a schematic sectional view illustrating the scrubbing stationbefore supplying a substrate in both-face scrubbing process;

FIG. 17 is a schematic sectional view illustrating the scrubbing stationafter supplying the substrate in both-face scrubbing process;

FIG. 18 is a schematic sectional view illustrating the scrubbing stationin both-face scrubbing operation;

FIG. 19 is an enlarged sectional view for showing the relation betweenthe substrate and clamp groove in both-face scrubbing process;

FIG. 20 is a block circuit diagram illustrating a displacement sensorused in the present invention; and

FIG. 21 is a schematic representation of a conventional scrubbingapparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described in detail by way of theembodiments illustrated in the attached drawings. In these embodimentsis used a semiconductor wafer as an example of a substrate. However, thepresent invention is also applicable to other thin plates such as Glassplate, alumina plate, crystal plate, ceramic plate, sapphire plate,aluminum disc and the like. Referring to FIG. 1, a scrubbing apparatus Aincludes a scrubbing station E for scrubbing a substrate 1, atransportation robot C for transporting the substrate 1 into and out ofthe scrubbing station E, a loader B for supplying the substrate 1 to thetransportation robot C, an unloader D for storing a scrubbed substrate1, a controller F for controlling the entire apparatus, and a main bodyG for accommodating these components.

The loader B prepares an unscrubbed substrate 1 accommodated in acassette 54; which is raised or lowered step by step in synchronizationwith the take-out operation of the transportation robot C to move theunscrubbed substrate 1 into a predetermined position.

The unloader D prepares an empty cassette 54 for accommodating ascrubbed substrate 1 to be transported by the transportation robot Cafter the back-face scrubbing at the scrubbing station E. The cassette54 is raised or lowered step by step in synchronization with the supplyof the substrate 1.

The transportation robot C takes the unscrubbed substrate 1 out of theloader B to supply the substrate 1 to the scrubbing station E. After theback-face scrubbing at the scrubbing station E, the transportation robotC removes the scrubbed substrate 1 from the scrubbing station E totransport the substrate 1 to the unloader D.

At the location of the transportation robot C, an ultraviolet raygenerating lamp 88 is provided as a dust removal means J. The operationof the ultraviolet ray generating lamp 88 will be described later.

The structures of the loader B, unloader D, and transportation robot Care well known in the art, and therefore will not be described in detailherein.

FIGS. 2 and 3 are sectional views of the scrubbing station E inaccordance with the present invention. A substrate chuck 6 is slidablymounted on a upper-rotary housing 10 by way of sliders 9.

The substrate chuck 6 is of annular shape and divided into three pieces.The chuck diameter of the substrate chuck 6 is scalable, as can be seenfrom FIGS. 4 and 5. The substrate chuck 6 has a self-centering clampgroove 4 formed along inner circumference thereof so as to chuck theentire periphery of the thin substrate 1.

FIG. 6 is a partially enlarged sectional view of the self-centeringclamp groove 4 which is formed in the inner circumference of thesubstrate chuck 6. The self-centering clamp groove 4 is defined by theinside surface 4a abutting against the circumference of the substrate 1,a jaw 5 positioned at the lower end of the inside surface 4a forsupporting the lower tapered surface of the substrate 1, and an upperslide oblique surface 4b positioned above the jaw 5. In the embodimentshown in FIG. 6, the upper slide oblique surface 4b is slightly curvedto be followed by the inside surface 4a and has such sectionalconfiguration as the surface line is slightly waved in S-shape.Therefore, the periphery of the substrate 1 received in theself-centering clamp groove 4 slightly slides along the upper slideoblique surface 4b and fits within the inside surface 4a, and thetapered peripheral portion of the substrate 1 is supported by the jaw 5.The jaw 5 is slightly engaged with the lower tapered surface of thesubstrate 1, and does not project downwardly of the surface to bescrubbed 1a (the lower face) of the substrate 1. The surface to bescrubbed will hereinafter be called "scrub surface" for convenience.

A plurality of fluid drain through-holes 11 are formed at certainintervals in the vicinity of the inner circumference of the substratechuck 6, and the major axis of the elliptical through-hole 11 extendsalong the tangent line of the self-centering clamp groove 4. The fluiddrain through-hole 11 extends downwardly obliquely from the insidesurface to the lower surface of the substrate chuck 6. Fluid dischargedonto the back pressure applied surface 1b of the substrate 1 is smoothlydrained through the fluid drain through-holes 11 to the lower side ofthe substrate chuck 6.

Three pieces of the substrate chuck 6 are connected by means of scalableguides 12 fixed onto roller mounting blocks 70b. A slide member 12a ofthe scalable guide 12 is slidably held in a slide opening 71a formed ina roller mounting block 70a of the adjacent substrate chuck piece 6. Asshown in FIG. 4, the clearance between adjacent substrate chuck pieces 6is expanded by inserting an expansion cylinder head 14 between expansionrollers 13 provided at the ends of the adjacent pair of the substratechuck pieces 6. At this time, the slide member 12a is moved away fromthe side opening 71a.

The scalability of the substrate chuck 6 is slidably adjusted by sliders9 provided on the lower side of the substrate chuck 6. The chuckdiameter of the substrate chuck 6 is increased by the expansion cylinderheads 14 as described above, and is reduced by chuck diameter reductioncylinders 15 each provided in a position opposite the expansion cylinderhead 14. That is, the substrate chuck 6 is pushed inward by theoperation of the chuck diameter reduction cylinders 15, and the slidemembers 12a are pushed back into the slide openings 71a, whereby theentire substrate chuck 6 is closed as shown in FIG. 5. At this time, theexpansion cylinder heads 14 are pulled back.

When the substrate chuck 6 is closed to chuck the periphery of thesubstrate chuck 1 within the self-centering clamp groove 4, one of thescalable guides 12 is locked by a lock mechanism H. Therefore, thesubstrate chuck 6 does not open by centrifugal force generated by therotation of the substrate chuck 6. The lock mechanism will be describedlater.

The upper rotary housing 10 is connected to a rotary drum 17 by means ofa rotary head cover 16. A coupled driving pulley 18 is mounted to therotary drum 17 and connected to a driving pulley 20 of a motor 21 forrotating substrate by means of a driving belt 19. Accordingly, thetorque of the motor 21 for rotating substrate is transmitted to thecoupled driving pulley 18 to rotate the substrate chuck 6. A positioningcam 22 is mounted to the coupled driving pulley 18. A positioning camfollower 23 is adapted to be fitted into the groove of the positioningcam 22 so that the substrate chuck 6 can be forcibly stopped in apredetermined position at any time. To ensure that the positioning camfollower 23 is exactly received in the groove of the positioning cam 22at any time, the stopping position is always monitored by a positioningsensor. This is well known in the art, and therefore will not bedescribed in detail herein.

A stationary housing 24 is fitted around the rotary drum 17, androtatably supports the rotary drum 17 by means of a bearing.

A stationary splash protection cover 25 is provided on top of thestationary housing 24. Posts 27 are erected upwardly of a base plate 26and a stationary block 29 is fixed on top of the posts 27.

A stationary head cover 28 is mounted on top of the stationary block 29,and covers the rotary head cover 16.

A substrate support cylinder rod 30 is slidably inserted into the centerof the stationary block 29, and is elevatably driven by a substratesupport operation cylinder 31 disposed below the stationary block 29.

A substrate support intermediate member 32 having a V-shaped crosssection is mounted on top of the substrate support cylinder rod 30, andsubstrate support rods 33 are erected upwardly of the substrate supportintermediate member 32. In this embodiment, four substrate support rods33 are provided, and their tip port ions are covered with support heads35 with cushion members 34 being interposed.

A fluid receiving member 36 having a V-shaped cross section is providedbelow a cylindrical brush 3.

Brush elevation bars 37 are slidably inserted into the stationary block29. A brush elevation cylinder 38 is disposed at the lower end of thebrush elevation bars 37 to raise and lower the brush elevation bars 37.On top of the brush elevation bars 37, a brush mounting member 39 ismounted to rotatably support the cylindrical brush 3 thereon.

The cylindrical brush 3 is rotatably supported around a rotary shaft 40,at one end of which a coupled brush driving pulley 41 is attached. Abrush driving belt 42 is suspended on the coupled brush driving pulley41, and is connected to a brush driving pulley 43 of a brush drivingmotor 44 to transmit the torque of the brush driving pulley 43 to thecylindrical brush 3. In this embodiment, a highly water-absorptive buffis used as the. cylindrical brush 3, but not limited thereto.Long-haired or short-haired brushes are also used, depending onapplications.

A drain pipe 45 is provided in the stationary block 29, and drains thefluid fallen onto the stationary block 28. A wash fluid jet nozzle 46 isconnected to a wash fluid supply pipe 47 provided in the stationaryblock 29 to jet the wash fluid against the cylindrical brush 3 from thetip of the wash fluid jet nozzle 46. In this embodiment, high puritywater is used as the wash fluid, but not limited thereto. Liquid such asalcohols, and inept gases such as nitrogen and argon gases are alsousable as the wash fluid.

If extremely high purity water is used as a fluid 2 for generating backpressure, electrostatic charge may be built up in the substrate 1.Therefore, it is desirable to use high purity water with lower electricconductivity which contains carbon dioxide gas, in terms of theprevention of electrostatic charge.

If a gas is used as the wash fluid, it is also desirable to previouslytreat the gas by means of an ionizer.

A back pressure paddle 7 disposed right above the cylindrical brush 3 isadapted to be moved upwardly and downwardly with respect to thesubstrate 1, and is formed with a fluid jet outlet 7a at the centerthereof. The fluid jet outlet 7a may be formed as a single hole opposingto the center of the substrate 1 and positioned right above thecylindrical brush 3, as a plurality of holes provided in a line alongthe cylindrical brush 3, or as a slit. In this embodiment, a slit-shapedfluid jet outlet 7a is formed in the lower surface of the back pressurepaddle 7, and the back pressure-fluid is discharged therefrom.

As described above, an inert gas such as nitrogen gas or liquid such ashigh purity water is used as the back pressure fluid.

A displacement sensor 48 is disposed within the back pressure paddle 7.The output from the displacement sensor 49 is input to one terminal of acomparator 50, and compared with a reference voltage. The output fromthe comparator 50 indicative of a displacement amount is input to adriver 51. Based on the input, the driver 51 drives a regulator 52 toregulate the jet pressure of the back pressure fluid 2 discharged fromthe fluid jet outlet 7a. A fluid supply source 53 supplies the fluid 2to the regulator 52 at a constant pressure. A block diagram illustratingthe back pressure regulation mechanism is shown in FIG. 20.

There is now described the charge removal means J disposed at thelocation of the scrubbing station E and transportation robot C. In thisembodiment, a lamp 86 such as deuterium lamp, mercury lamp, or barrierlamp is used as the charge removal means J, but not limited thereto.Electrostatic charge may be otherwise removed: (1) with an ionizer usingcorona discharge; (2) with isotopes; (3) with electron beam; (4) withplasma; and (5) with soft X-radiation. The use of lamp is the mostconvenient among these means, and does not generate harmful dustparticles. This embodiment takes an example of dust-free charge removalmechanism using the aforementioned lamp for generating ultraviolet ray.

The charge removal mechanism using lamps 88 and 89 will be brieflydescribed herein. The lamps 88 and 89 generate ultraviolet ray. A shortwavelength ultraviolet ray serves to electrically neutralize the surface1a of the substrate 1 to be made dust-free by ionizing the ambient gasat the location of the irradiation. A long wavelength ultraviolet raygenerates photoelectrons to remove electrostatic charge from thesubstrate 1. That is, the ultraviolet ray generates photoelectrons fromits sealed glass tube to remove positive electric charge from thesubstrate 1, and impinges on a charged body (substrate 1) which itselfgenerates photoelectrons to remove negative electric charge.

There are three types of mercury lamps--extra-high pressure mercurylamp, high pressure mercury lamp, and low pressure mercury lamp. The lowpressure mercury lamp is suitable for the use of short wavelengthultraviolet ray.

When ultraviolet ray is used for the charge removal, it is important todirectly apply the Ultraviolet ray onto the charged substrate 1. Sincethe generation of photoelectrons is enhanced with an increased energy,it is desirable to use short-wavelength and high-intensity ultravioletray.

There is-now described the lock mechanism H. The lock mechanism H gripsthe guide lock 12c of the scalable guide 12 to prevent the substratechuck 6 from being expanded by the centrifugal force generated by therotation of the substrate chuck 6. A pair of roller mounting blocks 70aand 70b are provided at the juncture 6a of the substrate chuck pieces 6.A locking block 70c is integrally connected to the roller mounting block70a, and an isolation gap 68 is formed between the roller mounting block70a and locking block 70c. A locking shaft base 67 is erected on the topof the upper rotary housing 10, and extends through to the opening sideof the locking block 70c. An operation lever 61 of a reversed U-shape isprovided above the locking block 70c. A lock shaft 66 extends through ahorizontal lock shaft 62 disposed parallel to the operation lever 61,and is hight-adjustably fixed by an adjusting nut 62a. The lock shaft 66and lock shaft base 67 are integrally formed.

Lock lever mounting bars 62b are fixed to the horizontal lock shaft 62,and swivels with the pivotal movement of the horizontal lock shaft 62.Lock rollers 63 are rotatably fixed to roller mounting shafts 64 at thelower end of the lock lever mounting bars to press down the opening sideof the locking block 70c. A stopping block 72 is mounted on a blockmounting platform 65 provided on the periphery of the upper rotaryhousing 10, and provided with a stop recess 72a at its side wall toreceive a stop bolt 73 projecting from the lower portion of the lockingblock 70c. An elevatable lever operation block 74 is provided above thestopping block 72. A lock cylinder 60 is fitted into the lever operationblock 74. A cylinder rod 60a of the lock cylinder 60 is fit into thestopping block 72 to move the lever operation block 74 upwardly anddownwardly. The lever operation block 74 is formed with a leveroperation recess 74a to receive the operation lever 61. An elevationguide 75 is erected upwardly of the stopping block 72, and slidablyfitted into the lever operation block 74 to guide the lever operationblock 74 to be raised or lowered.

Referring to FIG. 1 and FIGS. 12 to 14, the operation of the presentinvention will be hereinafter described. A cassette 54 accommodatingmultiple substrates 1 is prepared at the loader B, and an empty cassette54 is provided at the unloader D. By the operation of the controller F,the transportation robot C takes a substrate 1 out of the loader B, andsupplies the substrate 1 to the scrubbing station E. At this time, thesubstrate chuck 6 is expanded by means of the expansion head 14 as.shown in FIG. 4, and the substrate 1 clamped at its periphery by thetransportation robot C is inserted into the expanded chuck 6.

At this time, the substrate support rods 33 raised by means of thesubstrate support operation cylinder 31 projects upper than theself-centering clamp groove 4 of the substrate chuck 6 to abut againstthe scrub surface 1a of the substrate 1. When the substrate 1 is placedon the support heads 35 of the substrate support rods 33, thetransportation robot C disengages from the periphery of the substrate 1to release the substrate onto the support heads 35. In turn, thesubstrate support operation cylinder 31 performs a reverse operation tomove downwardly and stops at a position such that the substrate 1 isaligned with the self-centering clamp groove 4. FIG. 6 is enlarged viewillustrating the current structural relation between the substrate chuck6 and substrate 1. As shown in phantom in FIG. 6, the substrate 1 issupported within the inside surface 4a of the substrate chuck 6 in aposition slightly upper than the self-centering clamp groove 4. When thesubstrate chuck 6 is closed by the means of the chuck diameter reductioncylinder 15, the periphery of the substrate 1 is brought into contactwith the upper slide oblique surface 4b of the self-centering clampgroove 4, and then moves downwardly along the upper slide obliquesurface 4b so as to be exactly fitted into the inside surface 4a. Atthis time, the jaw 5 of the substrate chuck 6 abuts against the taperedlower face of the periphery of the substrate 1, and therefore the lowersurface of the substrate chuck 6 does not project downwardly of thescrub surface 1a of the substrate 1.

After the substrate 1 is clamped by the self-centering clamp groove 4 ina self-centering manner, the substrate support rods 33 are furtherlowered by means of the substrate support operation cylinder 31 so as tobe apart from the scrub surface 1a of the substrate 1. During thisoperation, the transportation robot C returns to the home position, andstands by for the completion of the scrubbing of the substrate 1 toremove the substrate scrubbed from the scrubbing station E. After thetransportation robot C returns from a position above the substrate 1 tothe home position, the back pressure paddle 7 moves down and stops rightabove the back pressure surface 1b of the substrate 1. On or aftermoving down, the back pressure paddle 7 jets the back pressure fluid 2against the back pressure surface 1b of the substrate 1 to apply backpressure thereon. The cylindrical brush 3 standing by below thesubstrate 1 is moved upwardly by means of the brush elevation cylinder38 so as to be brought into contact with the scrub surface 1a of thesubstrate 1. At the same time, wash liquid is jetted from the wash fluidjet nozzle 46 toward the cylindrical brush 3 to wet the cylindricalbrush 3. The cylindrical brush 3 rotated by means of the brush drivingmotor 44 scrubs the scrub surface 1a of the substrate 1. During thescrubbing operation by the cylindrical brush 3, the upper rotary housing10 is rotated by means of the substrate rotating motor 21 to rotate thesubstrate 1 chucked by the substrate chuck 6 within the plane of thesubstrate 1. Since the scrub surface 1a of the substrate 1 brought intoline contact with the cylindrical brush 3 is rotated within the planethereof, the entire scrub surface 1a of the substrate 1 is scrubbed bythe cylindrical brush 3 at a high speed.

In addition, since the cylindrical brush 3 extends outwardly beyond thecircumference of the substrate 1 toward the substrate chuck 6 and thejaw 5 does not project downwardly of the scrub surface 1a as shown inFIG. 6, the entire scrub surface can be scrubbed without leaving almostany unscrubbed surface portion. As described above, a gas such nitrogengas or liquid such as high purity water is used as the back pressurefluid 2 jetted from the back pressure paddle 7.

If a liquid is used as the back pressure fluid 2, a plurality of fluiddrain through-holes 11 extending from the inside surface 4a to the lowersurface of the substrate chuck 6 are provided along the self-centeringclamp groove 4 and, therefore, during the rotation of the substratechuck 6, the back pressure fluid on the substrate 1 is drained throughthe fluid drain through-holes 11 to the lower side of the substratechuck 6, and no back pressure fluid remains undrained.

The fluid drain through-holes 11 are of oval or ellipticalconfiguration, and the major axis of the through-hole extends along thetangent line of the annular self-centering clamp groove 4.

There is now described the operation of the lock mechanism H. When thesubstrate chuck 6 is rotated during the scrubbing, the substrate chuckpieces 6 are to be radially moved by the centrifugal force so that thechuck diameter of the self-centering groove 4 will be increased.However, the chuck diameter reduction cylinder 15 reduces the chuckdiameter of the substrate chuck 6. Thereafter, the lever operation block74 is raised by means of the lock cylinder 60, and the operation lever61 engaged with the lever operation recess 74a is pivoted upwardly. Thelock lever mounting bars 62b are swiveled clockwise (in the figure)about the horizontal lock shaft 62 fixed to the operation lever 61. Thelock roller 63 is forcibly pressed down on the surface of the lockingblock 70c to shrink the gap of the locking slit 69, whereby the guidelock 12c inserted into the locking through-hole 71c is firmly gripped.

In this-operation, when the lever operation block 74 is raised by meansof the lock cylinder 60, a stopping bolt 73 is engaged with the stoppingrecess 72a. Therefore, excessively large bending force is not exerted onthe substrate chuck 6.

The lock roller 63 maintains the guide lock 12c in the locked state bythe resilience, or the clicking action of the locking block 70c. Whenthe substrate chuck 6 is rotated with this situation, the operationlever 61 and the stopping bolt 73 are disengaged respectively from thelever operation recess 74a and the stop recess 72a, and the substrate 1is rotated with the substrate chuck 6 being kept in a locked state asshown in the figure. Therefore, the lock cylinder 60 and members mountedthereon do not rotate with the substrate chuck 6. The lock mechanism His rotated with the substrate chuck 6 in the locked state. However,since only the members necessary for locking are mounted on thesubstrate chuck 6, the reduced weight of the substrate chuck 6facilitates the rotation of the substrate chuck 6.

When the scrub surface 1a of the substrate 1 is scrubbed by thecylindrical brush 3, the displacement sensor 49 provided on the backpressure paddle 7 always detects the distance between the substrate 1and the displacement sensor 49. The flow rate of the back pressure fluid23 jetted against the back pressure surface 1b from the back pressurepaddle 7 is controlled so that the distance between the substrate 1 andthe displacement sensor 49 is kept constant, based on the feedback fromthe displacement sensor 49. Therefore, the contact pressure of thecylindrical brush 3 is properly balanced with the back pressure on thecentral portion of the substrate 1, whereby the entire scrub surface 1aof the substrate 1 can be sufficiently scrubbed.

In view of the relation between the back pressure paddle 7 and thecylindrical brush 3, the slit of the fluid jet outlet 7a of the backpressure paddle 7 extends along the cylindrical brush 3, so that theback pressure is linearly applied onto the substrate 1. Therefore, thescrub surface 1a of the substrate 1 kept afloat with its periphery beingsupported by the self-centering clamp groove 4 can be scrubbed with thecylindrical brush 3 by applying sufficient pressure thereto.

When the scrubbing of the substrate 1 is completed, the brush elevationcylinder 38 performs a reverse operation and moves downwardly, wherebythe cylindrical brush 3 moves away from the scrub surface 1a of thesubstrate 1. At the same time, the brush driving motor 44 is turned offto stop the rotation of the cylindrical brush 3.

At this time, the discharge of the back pressure fluid 2 from the backpressure paddle 7 is stopped to cease applying the back pressure ontothe substrate 1, and the back pressure paddle 7 is moved upwardly. Ofcourse, the jetting of wash fluid from the wash fluid jet nozzle 46 isstopped. After the cylindrical brush 3 and the back pressure paddle 7are moved away from the substrate 1, the revolution of the substraterotating motor 21 is increased, thereby increasing the rotation speed ofthe upper rotary housing 10. Accordingly, the liquid adhering on thesurface of the substrate 1 is blown off by the centrifugal force anddrained through the fluid drain through-holes 11, and thus the substrate1 is dried.

Electrostatic charge may be generated on the substrate 1 by the frictioncaused by the contact between substrate 1 and rotating cylindrical brush3 and/or the wash liquid such as high purity water duping the scrubbingoperation, and also by the friction caused by the contact between thesubstrate 1 and the ambient air during the drying operation by the highspeed revolution. However, the electrostatic charge on the substrate 1can be removed by the aforementioned charge removal mechanism, that is,by irradiating ultraviolet ray on the substrate 1 with the chargeremoval means J during and after the drying operation.

After the drying and charge removal of the substrate 1, the substratechuck 6 is stopped rotating at an exact position such that the operationlever 61 is aligned with the lever operation block 74. To preciselycontrol the stop position of the operation lever 61, the positioningsensor 23 detects the rotational position of the upper-rotary housing 10to fit the positioning cam follower 23 into the positioning cam 22.

When the operation lever 61 is stopped at the position aligning with thelever operation block 74 and the operation lever 61 is received into thelever operation recess 74a, the lock cylinder 60 performs a reverseoperation to lower the lever operation block 74, thereby pressing downthe operation lever 61 fitted into the lever operation recess 74a.Further, the lock lever mounting bars 62b are swiveled counterclockwise(in the figure) about the horizontal lock shaft 62 fixed to theoperation lever 61, so that the lock roller 63 is disengaged from thesurface of the locking block 70c. Accordingly, the locking slit 69 iswidened by the resilient force of the locking block 70c, and the guidelock 12c is released from the gripping of the locking through-hole 71cto become slidable.

Thereafter, the expansion cylinder head 14 is inserted again between thepair of the expansion rollers to expand the clearance 6a as shown inFIG. 4. Accordingly, the diameter defined by the inside surface 4a ofthe substrate chuck 6 is increased, whereby the substrate 1 is releasedfrom the self-centering clamp groove 4.

There is now described the operation after the upper-rotary housing 10is stopped. After the upper-rotary housing 10 is stopped, the substratesupport operation cylinder 31 operates again to raise the substratesupport rods 33, so that the cushion members 34 provided at the tips ofthe substrate support rods 33 are brought into contact with the scrubsurface 1a of the substrate 1. At this time, the support heads 35 areslightly deformed by the spring force of the cushion members 34.

After the scrub surface 1a of the substrate 1 is supported by thesupport heads 35, the substrate chuck 6 is expanded as described above,and the substrate 1 is released from the self-centering clamp groove 4of the substrate chuck 6 and supported only by the support heads 35. Thesubstrate support operation cylinder 31 is operated with this situationto eject the substrate 1 upwardly of the substrate chuck 6. The ejectedsubstrate 1 is removed by the transportation robot C.

The transportation robot C once returns to the home position, and thentransports the substrate 1 to the unloader D. At this time,electrostatic charge generated by the friction between the substrate 1and the ambient air is removed by the ultraviolet ray generating lamp 88provided as a charge removal means at the home position of thetransportation robot C.

After the uncharged substrate 1 is transported to the unloader D by thetransportation robot C, the substrate 1 is inserted into the emptycassette 54 mounted on the unloader D. Thus, the one-face scrubbing (orback-face scrubbing) of one substrate is completed.

In some cases, both-face scrubbing (or front- and back-face scrubbing)may be required depending on the types of substrates 1 or by a requestfrom manufacturing sites. There is now briefly described the both-facescrubbing. A substrate chuck 6 for both-face scrubbing has a clampportion, the width of which is less than the thickness of a substrate 1.A self-centering clamp groove 4 is formed on the inside circumference ofthe clamp portion, and the tapered periphery of the substrate 1 ischucked by the substrate supporting jaws 5a and 5b of a jaw member 5.

Brushes 3a and 3b movable upwardly and downwardly are brought intocontact with the both faces of the substrate 1 to simultaneously scrubthe both faces of the substrate 1. Accordingly, the difference betweenthe both-face scrubbing and one-face scrubbing shown in the firstembodiment is that the back pressure paddle 7 is replaced by an upperside brush 3b.

After the completion of the scrubbing, the scrubbed substrate 1 isremoved from the scrubbing station E, transported to an unloader D, andinserted to an empty cassette 54 mounted on the unloader D by atransportation robot C. Thus, the both-face scrubbing of the substrate 1is completed. In this case, charge removal means J are disposed on theboth sides of the substrate 1 to apply ultraviolet ray onto the bothfaces of the substrate 1.

The method and apparatus for scrubbing substrate of the presentinvention present an excellent ability to scrub either face or bothfaces of a semiconductor substrate. Since the contact pressure of abrush is balanced with an appropriate back pressure or the contactpressure of another brush provided on the side of the front face of thesubstrate during the scrubbing operation, the warpage of the centralportion of the substrate can be prevented, whereby even the centralportion of the substrate can be sufficiently scrubbed. In addition,since chuck jaw does not project outwardly of the scrub surface andtherefore the cylindrical brush can be applied onto the substrate overthe chuck jaw, no portion of the substrate remains unscrubbed. Further,since fluid drains are provided along a clamp groove, fluid on thesubstrate can be smoothly drained from the fluid drains by centrifugalforce generated by the rotation of the substrate chuck and thesubstrate, and no fluid on the substrate remains undrained. Therefore,the front face as well as the back face of the substrate can be alwayskept clean.

Still further, since a charge removal means is provided, electrostaticcharge can be removed even if the substrate is charged after scrubbing.Therefore, dust particles suspended in the air will not adhere on thescrubbed surface, and the substrate will be kept as clean as just afterthe scrubbing.

Although the present invention has been described in detail with respectto specific preferred embodiments thereof, various changes andmodifications may be suggested to one skilled in the art and it isintended that the present invention encompasses such changes andmodifications as fall within the scope of the appended claims.

What is claimed is:
 1. An apparatus for scrubbing a substratecomprising:a substrate chuck adapted to surround the substrate andhaving a clamp groove formed therein for receiving generally entireperipheral portion of the substrate and fluid drain through-holesprovided along the clamp groove and extending from the upper surface tothe lower surface thereof; a back pressure paddle for jetting fluid forgenerating back pressure against the face opposite a face to be scrubbedof the substrate to apply back pressure to the substrate; a cylindricalrotary brush adapted to contact the face to be scrubbed of the substratefor scrubbing the same; and a rotation mechanism for rotating thesubstrate chuck or the cylindrical rotary brush within a plane parallelto the substrate.
 2. An apparatus according to claim 1, furthercomprising a charge removal means provided in a substrate scrubbingstation and/or a substrate transporting path for removing electrostaticcharge on the substrate after the completion of scrubbing.
 3. Anapparatus for scrubbing a substrate comprising:substrate chuck adaptedto surround the substrate and having a clamp groove formed therein forreceiving generally entire peripheral portion of the substrate and fluiddrain through-holes provided along the clamp groove and extending fromthe upper surface to the lower surface thereof; upper and lowercylindrical rotary brushes provided on both sides of the substrate andadapted to contact both faces of the substrate, respectively, forscrubbing the both surfaces of the substrate; and a rotation mechanismfor rotating the substrate chuck or the upper and lower cylindricalrotary brushes within a plane parallel to the substrate.
 4. An apparatusaccording to claim 3, further comprising a charge removal means providedin a substrate scrubbing station and/or a substrate transporting pathfor removing electrostatic charge on the substrate after the completionof scrubbing.
 5. An apparatus for scrubbing a substrate, comprising:asubstrate chuck adapted to surround the substrate and having a clampgroove formed therein for receiving a periphery of the substrate; acylindrical rotary brush adapted to contact a scrub face of thesubstrate for scrubbing the scrub face from one end to the other; a backpressure paddle for jetting fluid against an opposing face of thesubstrate to apply back pressure to the substrate; and a rotationmechanism for rotating one of the substrate chuck and the cylindricalrotary brush within a plane parallel to the substrate, wherein saidsubstrate chuck includes chucking jaws projecting inwardly from theclamp groove of the substrate chuck to support the substrate such thatthe entire scrub face is exposed to the cylindrical rotary brush, thejaws are not exposed to the brush, and the opposing face is exposed tothe back pressure paddle.
 6. An apparatus according to claim 5, furthercomprising a charge removal means provided in a substrate scrubbingstation and/or a substrate transporting path for removing electrostaticcharge on the substrate after the completion of scrubbing.
 7. Anapparatus for scrubbing a substrate, comprising:a substrate chuckadapted to surround the substrate and having a clamp groove formedtherein for receiving a periphery of the substrate; upper and lowercylindrical rotary brushes provided on both sides of the substrate forcontacting both faces of the substrate from one end to the other endthereof for scrubbing both faces of the substrate; and a rotationmechanism for rotating one of the substrate chuck and the upper andlower cylindrical rotary brushes within a plane parallel to thesubstrate, wherein said substrate chuck includes chucking jawsprojecting inwardly from the clamp groove of the substrate chuck, suchthat the substrate is supported therein to expose each entire substrateface to the respective upper and lower cylindrical rotary brushes andnot to expose the jaws to the brushes.
 8. An apparatus according toclaim 7, further comprising a charge removal means provided in asubstrate scrubbing station and/or a substrate transporting path forremoving electrostatic charge on the substrate after the completion ofscrubbing.